Observation of collisions between cold Li atoms and Yb${}^{+}$ ions

Abstract

We report on the observation of cold collisions between ${}^6$Li atoms and Yb${}^{+}$ ions. This combination of species has recently been proposed as the most suitable for reaching the quantum limit in hybrid atom-ion systems, due to its large mass ratio. For atoms and ions prepared in the ${}^2{S}_{1/2}$ ground state, the charge transfer and association rate is found to be at least~10${}^3$ times smaller than the Langevin collision rate. These results confirm the excellent prospects of ${}^6$Li--Yb${}^{+}$ for sympathetic cooling and quantum information applications. For ions prepared in the excited electronic states ${}^2{P}_{1/2}$, ${}^2{D}_{3/2}$ and ${}^2{F}_{7/2}$, we find that the reaction rate is dominated by charge transfer and does not depend on the ionic isotope nor the collision energy in the range $\sim$~1--120~mK. The low charge transfer rate for ground state collisions is corroborated by theory, but the $4f$ shell in the Yb${}^{+}$ ion prevents an accurate prediction for the charge transfer rate of the ${}^2{P}_{1/2}$, ${}^2{D}_{3/2}$ and ${}^2{F}_{7/2}$ states. Using \textit{ab initio} methods of quantum chemistry we calculate the atom-ion interaction potentials up to energies of 30$\times 10^3$~cm${}^{-1}$, and use these to give qualitative explanations of the observed rates.

8 pages, 7 figures (including appendices)

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Cited by in corpus (4)

• Rotational state-changing collisions between N${}_2^{+}$ and Rb at low energies
• Experimental setup for studying an ultracold mixture of trapped Yb${}^{+}$-${}^6$Li
• Photon-mediated charge-exchange reactions between 39K atoms and 40Ca+ ions in a hybrid trap
• Interaction potentials and ultracold scattering cross sections for the ${}^7$Li${}^{+}$-${}^7$Li ion-atom system